Resolve And Pass Multiple Values From A Then
Let's say you are chaining multiple async function calls together.
```javascript
fetchTrainer(trainerName)
.then(response => {
const trainerData = response.body;
return fetchPokemonFor({ trainerId: trainerData.id });
})
.then(response => {
// I want trainerData, but it is now out of scope...
});
```
But in the last `then()` you want access to both the `trainerData` and the
`pokemonData`. So, how do you pass both the `trainerData` and the resolved
response of `fetchPokemonFor()` through to that last `then()`.
```javascript
fetchTrainer(trainerName)
.then(response => {
const trainerData = response.body;
return Promise.all([
trainerData,
fetchPokemonFor({ trainerId: trainerData.id })
]);
})
.then(([trainerData, pokemonResponse]) => {
const pokemonData = pokemonResponse.body;
// do something with trainerData and pokemonData
});
```
`Promise.all` allows us to resolve and pass multiple promises. If any of the
values in the array argument is not a promise, it simply passes it through.
h/t Brian Dunn
joshbranchaud
April 20, 2018